In recent years we have successfully developed many methods to overcome problems associated with static and radiofrequency (RF) magnetic field distortions inherent with high field human MRI, but many challenges still remain. For this renewal we propose to 1) determine optimal configurations of practical transmit RF arrays and pulsing methods for safe, versatile, homogeneous RF excitation in the head and body at several key field strengths, 2) develop a reliable, real-time method of ensuring RF safety in transmit arrays, where currently an infinite number of power absorption patterns are possible for a given array and subject and little is known about the safety implications, and 3) implement and demonstrate key progressive transmit arrays and pulsing methods for body and head imaging at a few key field strengths, along with a reliable RF array safety monitoring system. To accomplish these Aims we will continue the partnership between the Pennsylvania State University (PSU: Lead Investigator CM Collins), the University of Minnesota (UMN: Lead Investigators K Ugurbil and JT Vaughan), and Remcom, Inc. (Lead Investigator R Luebbers). The partnership will be led by PSU. The approach will be multidisciplinary in that it will require 1) numerical simulations of a) RF fields (PSU, Remcom) b) nuclear magnetic phenomena (PSU), and c) temperature and related physiology (PSU, Remcom) to guide development of RF hardware and pulses and the safety monitoring system, 2) RF hardware design and implementation (PSU, UMN), and 3) high field MRI experiments (PSU, UMN). With this project we will make significant improvements to Magnetic Resonance Imaging (MRI) Technology. We will develop, implement, and demonstrate technology to make MRI safer, faster, and more effective for all research and, eventually, medical applications.